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北秦岭西段唐藏石英闪长岩岩体的形成时代及其地质意义

陈隽璐1,2,徐学义1,王洪亮1,3,王宗起4,曾佐勋2,王超1,李平1   

  1. 1西安地质矿产研究所,陕西 西安710054;2中国地质大学 地球科学学院,湖北 武汉430074;3西北大学 地质学系,陕西 西安710069;4中国地质科学院 地质研究所,北京100037
  • 收稿日期:2007-09-03 修回日期:2007-12-18 出版日期:2008-01-20 发布日期:2008-01-20
  • 作者简介:游建昌,男,高级工程师,1956年出生,岩矿分析专业,从事X射线衍射分析研究工作。 Email: xrd@petrochina.com.cn。
  • 基金资助:

    国家科技支撑计划项目(2006BAB01A11);; 中国地质调查局国土资源大调查研究项目(1212010610319,1212010611807)

LA-ICPMS Zircon U-Pb Dating of Tangzang Quartz-diorite Pluton in the West Segment of North Qinling Mountains and Its Tectonic Significance

CHEN Jun-lu1,2; XU Xue-yi1; WANG Hong-liang1,3; WANG Zong-qi4; ZENG Zuo-xun2   

  1. 1Xian Institute of Geology and Mineral Resources, Xi'an,Shaanxi710054,China;2 Faculty of Earth Science,China University of
    Geosciences, Wuhan, Hubei430074,China;3Faculty of Geology,Northwest University, Xi'an,Shaanxi710069,China;
    4Institute of Geology, Chinese Academy of Geological Sciences, Beijing100037,China
  • Received:2007-09-03 Revised:2007-12-18 Online:2008-01-20 Published:2008-01-20

摘要:

在对陕西宝鸡一带进行地质大调查时,发现北秦岭造山带西段的唐藏石英闪长岩体具有埃达克岩的特征。利用阴极发光、LA-ICPMS方法对唐藏石英闪长岩的单颗粒锆石进行了U-Pb测年,所选锆石晶体均呈长柱状,振荡环带发育,Th/U=0.33~1.10,为典型的岩浆成因锆石。测试的29个样品的206Pb/238U加权平均年龄为(454.0±1.7)Ma,各测点206Pb/238U表面年龄与加权平均年龄在误差范围内近于一致,因此,这一数值代表岩浆生成年龄。结合北秦岭造山带西段代表洋壳残片的关子镇、岩湾蛇绿(混杂)岩形成时代,说明早古生代古秦岭丹凤洋沿商丹带一线向北发生俯冲消减作用,(454.0±1.7)Ma可能代表俯冲消减的初始时期。研究结果为北秦岭早古生代造山作用过程、壳幔相互作用及大陆动力学的研究提供了重要的依据。

关键词: 锆石, 埃达克岩, LA-ICPMS测年, 唐藏石英闪长岩体, 北秦岭西段

Abstract:

The Tangzang quartz-diorite pluton which has the characteristics of Adakite was founded in a geological survey in Baoji,Shaanxi.Zircons from the quartz-diorite pluton are generally colorless and long columnar with obvious magmatic zone.The LA-ICPMS zircon U-Pb geochronology of 29 samples from the pluton with Th/U ratios from 0.33 to 1.10,yielded a weighted mean 206Pb/238U age of(454.0±1.7)Ma as the magmatic crystalline age of the protolith of the quartz diorite.Integrated the formation age of the Guanzizhen...

Key words: zircon, Adakite, LA-ICPMS dating, Tangzang quartz-diorite pluton, west segment of north Qinling orogenic belt

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